plangeo2 plangeo2.ocd 2006-06-01 experimental 2004-06-01 0 1 This CD defines symbols for planar Euclidean geometry. segment The segment of a line between two points of the line. The segment is contained in the affine part of the line. The symbol takes as arguments the two points. The segment AB: halfline The halfline starting at A and going through B. The symbol takes as arguments the points A and B. corner The corner between two halflines L and M, both starting at the same point. Given three points A, B and C, the corner A, B, C is the corner of the two halflines BA and BC. Corresponding to the two cases, the symbol can have as arguments two halflines or three points. or endpoint The endpoint of a halfline. The endpoint of a halfline H is given by endpoints The two endpoints of a segment. The set of the two endpoints of a segment S is given by